1. Field of the Invention
The present invention relates to an automatic setup apparatus for an image data converter for converting image data of an original to image data for recording in a color scanner or the like and a method of correcting a setup parameter decision characteristic in the automatic setup apparatus.
2. Description of the Prior Art
As is well known in the art, a process scanner, which enables high-quality image reproduction, is formed by an image reader for optically reading an image of an original, an image data converter for convering read image data to image data for recording, an image recorder for exposure-recording the image data for recording on a photosensitive film etc. and the like. In order to perform high-quality image reproduction with such a scanner, a large number of regulation items required for color separation processing, such as reproducibility of gradation as well as enhancement of resolving power and sharpness etc., and reproducibility of color tones particularly in a color scanner for reproducing a color image, must be set in response to various types of orginals, so that the image data for recording converted by the aforementioned image data converter enter optimum states.
For example, highlight densities and shadow densities for respective ones of color components of blue (B), green (G) and red (R), highlight and shadow output dot % for respective ones of collor films of yellow (Y), magenta (M), cyan (C) and black (K), selective color collection as to a specific color component in the original, gradation (gradation correction) and sharpness enhancement etc. can be cited as typical ones of the aforementioned regulation items in the color scanner. Such a large number of regulation items, i.e., setup parameters in an image data converter, are not fixed but varied with originals as well as requirements as to how the images are to be reproduced. Therefore, high-quality image reproduction is enabled by optimum regulation of the setup parameters.
FIG. 11 is a block diagram showing the structure of such a conventional color scanner. Referring to the figure, an image reader 2 scans an original 1 to read its image, and outputs R, G and B signals for color components of red (R), green (G) and blue (B) as image data. In an ordinary color scanner, an unsharp signal U is also outputted in order to generate a sharpness enhancement signal, although the same is not shown in FIG. 11. An image data converter 3 converts the R, G and B (and U) signals to image data for recording. Namely, the image data converter 3 performs a series of processes such as conversion from the R, G and B (and U) signals to Y, M, C and K signals for color separation of yellow (Y), magenta (M), cyan (C) and black (K), gradation correction, color correction, control for enhancement or suppression of sharpness, magnification conversion and the like therein.
In order to perform these processes, however, setup parameter values must be previously set in the image data converter 3, as hereinabove described. Therefore, an operator empirically determines appropriate setup parameter values in response to the contents of the original and finish requirements for reproduced images, and manually sets the setup parameter values in the image data converter 3 through a setup parameter input unit 4. The parameter input unit 4 is formed by a keyboard, a mouse and the like. The image data for recording converted by the image data converter 3 are exposure-recorded in the form of halftone dots on photosensitive materials such as films by an image recorder 5, whereby color separation films 6 are produced.
FIG. 12 is a block diagram showing the structure of another conventional color scanner. Referring to the figure, an automatic setup apparatus 10.sub.a comprises a frame memory 11 and an automatic setup parameter setting unit 12.sub.a which is formed by a CPU, while other elements are identical to the elements in FIG. 11. First, image data (R, G and B signals) obtained by prescanning an image reader 2 are stored in the frame memory 11. Then, the automatic setup parameter setting unit 12.sub.a automatically analyzes the image data stored in the frame memory 11, thereby obtaining setup parameters. Such an automatic analyzing method is disclosed in Japanese Patent Laying-Open Gazette No. 2-56175 or the like.
However, since the setup parameters obtained by the automatic setup parameter setting unit 12.sub.a are restricted to partial setup parameters such as highlight densities and shadow densities for the R, G and B signals in the present circumstances, an operator manually sets empirically determined values as to a large number of remaining setup parameters through a setup parameter input unit 4, similarly to FIG. 11.
Since the setup parameters for the image data converter are set in the aforementioned manner in the conventional scanner, there are the following problems:
First, a skilled operator is required in order to obtain preferable recorded image in the prior art shown in FIG. 11, since the setup parameters are appropriately set on the basis of experience of the operator.
Further, dependence on the ability of the operator leads to appearance of individual difference of the operator himself in the conversion results of the image data, whereby it is impossible to construct a flexible image data conveter reflecting user's preference and tendency of finish quality.
In the prior art shown in FIG. 12, on the other hand, the automatic setup apparatus 10.sub.a is introduced in order to solve the aforementioned problems. However, since the setup parameters obtained by this automatic setup apparatus 10.sub.a are restricted to parts of parameters required for image data conversion, the remaining most parts are empirically set by the operator himself, and hence the problems caused in the prior art of FIG. 11 are not yet solved in the prior art shown in FIG. 12.
Such problems are not restrictive to conversion of image data in a process scanner, but common to apparatuses for reading image data of originals, converting the same to image data for recording and thereafter restoring images of originals in high quality.